Added ImprovMX records.

domains/sigmacat.json

@@ -3,6 +3,8 @@
     "username": "SigmaCat01"
   },
   "records": {
-    "CNAME": "sigmacat.pages.dev"
+    "CNAME": "sigmacat.pages.dev",
+    "MX": ["mx1.improvmx.com", "mx2.improvmx.com"],
+    "TXT": ["v=spf1 include:spf.improvmx.com ~all"]
   }
 }